Furnace conveyor roll



United States Patent Pennsylvania Filed Feb. 24, 1958, Ser. No. 717,174 2 Claims. (Cl. 263-6) The present invention relates to furnaces, and more particularly to a conveying roller that is used to move work through a furnace while the work is being heated.

In furnaces of the roller hearth type there is provided a plurality of driven rollers upon which the work, such as plates, slabs or billets, is mounted, and by which it is moved from one end of the furnace to the other. These rollers are usually of a heat resisting alloy steel, and are usually provided with some cooling means. Ordinarily the cooling means is a bore through the center of the roll with provision for circulating cooling water through the bore.

In operating furnaces of the type in question a balance has to be reached between where the roll is heated to a temperature at which it loses its strength and a temperature where it is so cool that it has a marked effect upon the heating of the work. In the heating of heavy work pieces, strength of the conveyor rolls is ordinarily the more important consideration. Consequently, the rolls are maintained at a low enough temperature that they have a tendency to draw heat from the work with the result that the top and bottom parts thereof are heated to different temperatures.

It is an object of the invention to provide a conveyor roll, for use in a furnace, which will have strength without having a cooling effect on the work. It is a further object of the invention to provide a furnace conveyor roller that has a replaceable load bearing surface.

In following the invention there is provided a conveyor roll that extends across the furnace chamber and is journaled in bearings beyond the furnace sides. The roll is provided with water cooling which will keep it below a temperature at which it will lose its strength. A wear resisting shield in the form of a sleeve, or series of sleeves larger in diameter than the roll, surrounds it and supports the load thereon. This shield transmits sufficient heat to the roll so that the shield has a long service life, but is heated sufficiently by the furnace and the work so that it has no appreciable elfect on the temperature of the work.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a section through a furnace showing the conveyor roll in place;

FIG. 2 is a section taken on line 22 of FIG. 1; and

FIG. 3 is a view partly in section of a modified form of conveyor roll.

Referring to FIG. 1, there is shown a furnace 1 which is constructed in the usual fashion of refractory material 2 that is backed up by sheet metal work 3 to form a furnace chamber 4. It is intended that this furnace should be elongated in a conventional manner and should have a plurality of conveyor rolls extending through it at spaced points along its length with the rolls being located on centers close enough together to support the type of work that is to be heated by the furnace. It is Patented Aug. 28, 1-962 also contemplated that the furnace can be heated by any suitable means to the temperatures required for the type of heating that is to be carried out therein. The furnace is provided with a plurality or series of pairs of openings 5 that are aligned with each other in the side walls thereof. The conveyor rolls 6, mentioned above, extend through these openings in parallel relation and are supported by piers 7' that are provided at their upper ends with suitable bearings in which the rolls are journaled for rotation. As shown herein, the rolls can be rotated to move the work through the furnace by means of suitable and conventional gearing 8.

Each of the rolls is tubular in form and is made of a steel that is selected to have the strength required to support the weight of the work being heated in the furnace at the temperature the roll will reach. The rolls have a bore 9 therein into which extends a pipe 11 having a valve 12 in it. This valve is regulated to adjust the flow of cooling water through the pipe, which water is discharged from an outlet 13 formed at one end of the roll, with the water being received in a funnel 14 connected to a drain pipe 15.

The roll is provided with a pair of radially extending collars 16 that serve to locate along its length a load supporting shield or sleeve 17 of high temperature alloy steel. It will be seen from FIG. 2 that the sleeve will rest eccentrically thereon and engage only the upper surfaces of the roll as the latter is rotated.

In the assembly of the roll, one or both of the collars 16 can be made separable from the roll so that the sleeve can be moved axially into position, or the collars can be made an integral part of the roll and the sleeve can be formed as a sheet that is placed around the roll and its ends welded to form a cylinder.

It has been found in the operation of conventional roller hearth furnaces that the water cooled conveyor rolls, which are ordinarily used, extract so much heat from the furnace and from the work piece traveling over them that it is difiicult to heat the work to the proper temperature. In some cases where the work is a slab of steel, for example, which has a relatively great thickness, such as shown in the drawings, the upper portion of the work is heated to an appreciably higher temperature than the lower portion. This is due to extraction of heat from the work by the relatively cool roll as the work is moving thereover. When a conveyor roll is provided with a shield or sleeve larger than the roll, as shown in this application, the heat transferred by the work to the sleeve and by the sleeve to the roll is diminished to such an extent that the temperature differential between the work and the sleeve is small enough so that there is no appreciable effect on the heat transferred to the work by the furnace.

As an example of the invention, a conveyor roll five inches in diameter is used with a sleeve having an inside diameter of five and three-quarters inches and a thickness sufficient for strength and wear. In a furnace having a wall temperature of 2.400 F., when heat is transferred from the furnace walls to the roll and sleeve mainly by radiation and when enough water is circulated through the bore of the roll to keep its temperature at a safe value of 400 F. the temperature of the shield will be approximately 2035 F. or high enough to have no appreciable effect on the work.

Heat is transferred from the sleeve to the roll mainly by radiation. For every increment of roll length the area of the sleeve is larger than the area of the roll. At equilibrium conditions, each square foot of roll area receives a larger amount of heat from the sleeve, than each square foot of sleeve area receives from the furnace wall or load depending upon the ratio of the diameter of'ftlie slevetand the; diameter of the roll; The sleeve ternneratnre adjusts itself to the equilibrium heat flow condition. If the diameter of the sleeve is increased for a roll of a given size the temperature of the sleeve will increase: It is noted. that ifrthe= temgeratures of .the roll is -raised the'vtemp er ature; of the; sleeve. :will alsov =rise. The temperature at WhiClllilihfi-IQH is maintained determine, whether for a: givenrload, it should: be a canb'omor. an alloysteel.

7 Another form which -the.invention can take is ,showninzBIG. 3. of a thedrawings; In :this -form the ,rol l is providedtzwith a -plurality -of grooves 121- alongthe :loadbearingportiona Ai ing zl isareceived ineach oftthese grooves With v the rings. acting: as; the. loadv bearing, surface. It willfibe-seenrthat the. rings are. larger in diameter than the grooves so that they hang freely, fromlthesroll at the lowerp ortiontthereof, similar torthe sleeve shown in FIG. .Zsofthe drawings The collarsilfi may be ;dis-v pensedzwith in this form-of theinvention since the grooves 21.prevent.the ringstfromsmoving axially-of the roll In. this form of, the invention? there is less supporting surface for the .work than isgthevcasewith a continuous sleeve. Sineethe rings have a shortera-xial dimension than the'sleeve 17 of.- FIG. 1, rings of thetype shown in FIG; 3 arenotssuitable for: supgortingas. heavy a load as the sleeve of FIG. 1.

While in-.-a,ccordance With-I116 provisions of :the statutes, I have. illustrated :anddescribedthe best form of emibodiment ofwmy, invention";notw known-tor-me; it awilltbe apparent tosthoseskilled :in--the. art that changesmay be made in the form of the apparatus disclosed without departing from the spirit and scope of the invention set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. A conveyor. rolllused for; supporting. and conveying heated objects comprising 7 an elongated cylindrical body, a-cylindrical sleeveloosely' received on said body, the diameter of. said,sleeve being only, slightlylargen than that of said bbdy'b'ut large enough-to-hang loosely thereon whereby the interior of said sleeve engages said body only attitsrupper surface; as-said body v rotates; and is spaced from-said body at the *sides; and -bot-tom-thereof, saidbody being; tuibul-ar,. and. means. to; circulate cooling; water:

through -the center; of *said body;

2. A roll accord-ingto claim! 1- in-which-said .body; is

provided? with' radially extending; collars;- adjacent to the ends of said sleeve; said; collars: acting, tov prevent axial movement-;of. ,sa-id isleevealong 1 said body References Citedin thefile of this patent UNITED STATES-"PATENTS" 720, 90,4' Edwards; Feb. 17; 19 03 7 1,566,460 Montgomery Dec. 15,,1942-5 1,800,170. Diescher: Apr; 7, ,193-1 2,;023',- 126-. Fahrenwald; Dec; 3, ,19' 1 601- 550; Nan-.Touron a June 2A,-.1952: 

